When I bought my first SNK Neo Geo AES, I couldn’t make out if it was outputting a PAL or NTSC signal. Since I was using RGB I wasn’t really worried about how the colour was encoded, but I definitely did want 60hz output.
There is an area marked NTSC ONLY, but looking at it confused me, as I was sure (but couldn’t prove) that my console was outputting an NTSC signal, but this area had no components. You’ll notice a metal link on the Sony chip in the top right of the photo, after poking around with an continuity meter it’s easy to see that it’s grounding a pin on a nearby chip.
Just like the Mega Drive and SNES 50/60hz mods which work by supplying a GND or +5v signal to a specific chip, I guessed the same might apply here. So I removed the metal link, powered on the console and nothing had changed. Next I linked the 2 pads in the PAL square, the upper one was measuring 5v, switched the console back on and sure enough I had huge black borders top and bottom of the screen.
So, if the leg 64 on the nearby chip – LSPC2-A2 9305 E27 is left floating (not connected to anything) or has a GND signal then it’s 60hz, if it is linked to 5v then it’s a 50hz signal. Here’s a photo showing the chip in relation to the pads.